Starting device for alternating-current motors.



L. A. HAWKINS. STARTING DEVICE FOR ALTERNATING CURRENT MOTORS.

APPLICATION FILED SEW, 1907.

1,055,907. Patented Mar. 11, 1913.

Fig.1 /\47; AZ 1 WiGnesses: lnvenor' Laurerice AHawkins,

' ductiontype. --This-'type of motor, as is wellcuit or both.

civi an STATES "PATEnrr. OFFICE.

LAURENCE A. HAWKINS, OF SQHENECTADY, NEW YORK, ASSIGNOR TO GENERALELECTRIC COMPANY, A CORPORATION OF YORK.

STABTING DEVICE FOR ALTERNATING-CUBRENT MOTORS. 7

To all la/ am ,tmy 65am.-

ing at Schenectady, county of Schenectady,

State ofNew York, have invented certain.

new and useful ,lmp rovcments'in- Starting Devices forAlternatingrCurrent Motors, of

which the following is a specification.

This invention relates to the control of alternating-current motors, andhas for its object, the provision of-means. whereby mo tors ofthist-ypemay be started and brought up t running speedfina reliable. andefiicient-nianne z. .2

My invention relatesmore specifically to the starting ofsinglephaseflmotors of the in-.

known, will-EH01}- :start fronrrest without the employment :of specialstarting devices, such as an auxiliary starting-winding or. a phase--splitting device .con'nccted in the motor cir- Devices of thischaracter-are designcdIt-o be in circuit for? only a short period during:,-;W-.hichthe motor -is beingv brought up to. synchronism; and if leftin circuit. too long, .-Wlll become. overheated.

*Mea ns have. therefore been employed for changingthe connections soasto-cut outthis starting device. L

The object. of my inventionis to provide,

in connectionwith a device for changing the connections, meanswhe-reby'the circuitchanging switch can'rrotbe movedto running.position'until the motor has been brought up i to .the proper runningspeed I also provide means whereby the switch -is held in runningposition, and automatically returned to' the off. position upon thefailu re of voltage. I

In the accompanyingdrawings,- in which- I have shown'myinventionembodied in concrete mechanism, Figure 1 is a plan view ofrunning? T Referring; to thedrawi ng 10 is an insulatthe device showing"circuit connections, and

Figs. 2 an'd 3'showre'spectively'the circuit connections of i the motnrforl starting and ating with a series of the contact segmentsSpecification of Letters Patent.

' Application filed September 24; 1907. Serial No. 394,278. g

base.

f j w 17, 18,19, 20, 21, 221ml 23. enact 14 Be t known .that I, LaonsncsA. Hawfums, a citizen of the United States, resid- A magnet Winding 25of the solenoid type Patented lilar ll, 1913. v

is mounted adjacent to the. segments, as

shown, and is provided with a plunger or core 25, connected by means ofa link 26 with a latch 27 pivoted to the. base at 28.

A spring 29 holds the latch in the position shown when the magnet isdenergized, but

when the magnetis energized, the latch will The pin 30 on the arm 11 isas to be engaged by the shoulder 31 on the latch when, the magnet is.rcnergized,

The arrangement of circuit and mode of operation is as follows: Srepresents the primary windings-or stator' ot an induction motor shownwith a three-phase winding Yconnection.

R is the rotor or secondaryof the motor which may be of the usualsquirrel-cage type.

Two of the windings 32 and 33 are connected to the source of currentthrough segments 22 and 23 and contact 16, conductor conductor 35,segments 17 and 18, and

contact 1 The third winding 3.6 is connected through magnet 25 tosegment 20, throligh conductors 37 and-38. The resistance 39 isconnected 'from segment 21 to conductor38 as shown, and the 'reactance40 is connected to the winding 32; at 41 and to the segment 19. Theresistance 39 and i the reactance 40 constitute phase-splitting devicesfor displacing the phase in-a well 7 known manner.

conductor 35, segment 17, contact 14, segment 18 back to line at 42'.Current will also pass through from main 42 to segment- 23, contact 16,segment 21, resistance R39, conductor 38, magnet 25, conductor 37, Windings 36 and 32, segments 17 and 18, back to line; also from main 42 tosegment 22, thence through windings 33 and 36, magnet- 25, segment 20,segment 19, react-ance 40 and back to line, through segments 17 and 18.This gives the motor the necessary starting torque, which, therefore,starts to rotate. As soon as the magnet is energized, the latch 27 ismoved into the path of the pin 30, so that the arm or lever cannot bemoved out of contact with the segments. As the motor begins to speed up,the energy of the magnet 25 begins to decrease. -The decrease in th'eflow ofcurrent through this magnet as the motor speeds up is due to thefollowing cause: it. is a well known fact that a singlephase inductionmotor at starting has a simple, pulsating, unidirectional field due tothe single-phase current supplied thereto,

while when the motor is up to speed, a rotary field exists. In otherwords, the rota tion of a secondary member causes a crossmagnetizationwhich induces in the motor windings an electromotive force in quadrature with the impressed. electromotive force. Consequently, in thearrangement shown in Fig. 2, the magnet winding 25 at starting hasimpressed upon it a voltage due" only to the phase-splitting devices. Asthe motor speeds up the cross-magnetization rises and induces anelectromotive force in the primary Winding of the motor in quadrature tothe impressed electromotive force and counter to the electromotive forceof the phase-splitting devices. Consequently, as this counter-electromotive force increases,

the current through the magnet winding 25 falls, and when the motor isbroughtup to running speed, the energy of the magnet is practically zeroand the spring 29 therefore draws the latch 27 out. of the pathof thepin 30, so that the arm 11 may be moved into running position. \Vhenthis position is reached, the contact 15 bridges segment 20 and cont-actstud 24, the contact 15 passes off segment 19, and the contact 14 still.

bridges segments 17 and 18. Contact. 15 in passing off the segment 19opens the circuit of the reactance 40 and the circuit of wind ing 33 andresistance 39 is broken by the passing of the contact 16 off segments 21and 22. The circuits will then be as shown in Fig. 8, the magnet 25being energized as' follows: from main 42 and segn'ient 23, to contactstud 24, segment 20, conductor 38, magnet 25, conductor 37, windings 36and 32, segments 17 and 18, and back to line. The magnet thus being inseries with the main motor windings is again energized and draws thelatch 27 down so that the sbonider 31 engages the pin 30 and holds thearm ii in running position. Upon failure of voltage the magnet 25 willbe decnergized and the arm 11 will be retinrn'ed to the off position inthe usual manner.

It will be seen that I have provided a simple and efficient device forbringing the motor up to running speed without danger to the motor andalso for placing the motor in a protective position upon the failure ofvoltage. 4

Various modifications .of my invention will, of course, suggestthemselves to those skilled in the art,without departing from the spiritof my:- invention, the scope of which is set forth in the annexedclaims.

What I claim as new,'and desire to secure by Letters Patent'of theUnited States, is,

1. The combination with an alternatingcurrent 'motor having differentconnections of the windings for starting and running, of a switch biasedto the 01f position for changing said connections, andla magnet windingconnected to be energized in quadrature to the main motor windings forlimiting the operation of-said switc 7 2. The combination with analternating current motor having different connections of the windingsfor starting and running, of a switch biased to the off position forchanging said connections, a magnet winding connected tov bedecreasingly energized during starting, means'whereby the magnet isconnected in series withthe motor during running, and means controlledby the magnet? for holdingthe switch in the running position.

3. The combination with an alternating current motor having differentconnections of the windings for starting and running, of a switch biasedto the off position for changing said connections, a magnet windingconnected in the. motor circuit, and means controlled thereby forpreventing the movement of the switch to running position until themotor reaches a predetermined speed.

4. The combination with an alternatingcurrent motor having differentconnections of the windings for starting and running, of a switch biasedto the off position for changing said connections, a magnet-windingconnected in the motor circuit, and means con- .trolled thereby forpreventing the move venting the movement of the switch to runningposition until the motor reaches a predetermined speed, and meanswhereby the and means controlled thereby for preventing the movement ofthe switch to running position until the motor reaches a predeterminedspeed.

7. The combination with an alternating current motor having difi'erentconnections of the windin for starting and twinning of a switch biasedto the oil position for changing said connections, a ma gnet winding forlimitin the movement of said switch and means w ereby when the switch ismoved to starting position the magnet is decreasingly energized 'dnringstarting and when the switch is moved to running position it isenergized in series with the motor. 8. 'The combination with analternating current motor having dint-rent connections of the windingsfor starting and running, of a switch biased to off position forchanging said eonnections,a magnet winding connected to be decreasinglyenergized duringstarting, means for connecting said magnet in serieswith the motor durifig running, and means'controiied by said magnet forpre ventingthe movement of the switch to run- .ning position until themotor reaches a predetermined 5 rd and then locking said switch inrunning position.

9. The Combination with a SlHQlWplHML induction motor andphase-splitting devices for starting said motor, of a switch biased tothe off position and arranged to cut said devices out of circuit, amagnet winding connected in circuit with the motor, and means controlledthereby for preventing the movefor starting saidmotor, 0

ment of the switch to running position when the magnet is energized andfor holding the switch in running position when running conditions areestablished.

10. The combination with a single-phase induction motor and phaseslitting devices i a switch arranged to out said devices out of circuit,a magnet connected .to be energized in quadrature to the main motorwindings, and means controlled by said magnet for preventing movement ofthe switch to running position while the magnet is energized.

..11. The combination with an alternating current motor having differentconnections of windings for starting and running, of a -switch;,thareforhavinga starting position between the off and therunning position an Ibiased to the of! POSltIOI], magnet windings connected to be energizedin quadrature to the main motor winding, and a latch controlled by saidmagnet and arranged to prevent movement of the switch to runningposition under Pl'ttlOlPl'llllllPtl conditions .of the motor circuit.

12. The combination with a single phase induction motor. aphase-splitting device for starting thesame, of a switch arranged to outsaid device out of circuit a magnet connected so as: to have impressedupon it an electromotive force due to the phase-split ting device duringstarting and connected in series with the motor during running. andmeans for preventing the movement of the switch to running positionuntil the motor reaches a predetermined speed and then locking theswitch in running position.

13. The combination with a single-phase induction motor and phasesplitting device for starting the same, of a switch biased to the oilposition and arranged to cut said device out of circuit, a magnetwinding connected to be energized in quadrature to the main inotorwindings when the switch is in a starting position, connections wherebysaid magnet is reds gized when the switch is moved to running position,a device controlled by said magnet. for preventing the movement of theswitch to running position until the magnet is deenergized and forlot-king the switch in running position when the magnet "ei nergized.

14. The en nation with an alternating current motor of a starting switchtherefor biased to off position, a magnet winding for controlling saidswitch connected so as to be derreasingly energized during starting andmeans for connecting said magnet in series with the motor duringrunning.

15. A starting device for electric motors comprising a switch biased tooil position, a

magniet winding having difierent connections" in the motor circuit rstartin and running, and means controlled there y for preventing themovement of the switch to running position until the motor reaches apredetermined speed, then holding the switch in running position.

. 16. A starting device for electric motors comprising a switch, biasedto off position a magnet winding connected in the motor circuit so as tobe decreasingly energized during starting of the motor, means wherebysaid magnet is caused to be energized uniforml during running, and alatch controlled by said magnet for preventing the movement of theswitch to running position until the motor reaches a predetermined speedand then holding the switch in running position.

17. A starting device for electric motors comprising a switch havin astarting posh tion between the off and t e running posi means forpreventing the movement of the switch to running position until themotor reaches a predetermined speed, and then holding the switch inrunning position.

181A starting device for electric motors comprising a switch having astarting position between the off and the running position and biased tothe off position, a magnet winding connected to be decreasinglyenergized during starting, means whereby said magnet is caused to beenergized uniformly during running, and lnea-ns controlled by saidmagnet for preventing the movement of the switch 'to running positionuntil the motor reaches a predetermined speed and for holding the switchin running position.

19. The combination with an electric niotor, of a starting devicetherefor comprising :1 switch biased to the 011' position, a magnetWinding having dilterent connections in the motor circuit duringstarting and running, and means controlled thereby for preventing themovement of the switch to running position until the motor reaches apredetermined speed, and then holding the switch in run ning position.

In witness whereof, I have hereunto set my hand this 23rd day ofSeptember, 1907.

LAURENCE A. llAlYKlNri.

Witnesses BENJAMIN B. HULL, l'leucx Oicronn.

Copies of this patent may be obtained for five cents each, by addressingthe "Commissioner or Patenh,

Washington, D. 0.

